Thermocouple pins

[Jman]

Hi all,

I am trying to wire thermocouples into my S8. I am aware that no linearization is needed within the software and the leads can be plugged directly into the designated ECU pins. The issue is with the pins on the connector. I use a connector similar to the following with pins connected to the sensor wires which make contact with the ECU pins:

http://www.efi101.com/forum/viewtopic.p ... f6a01820cd

To my knowledge there are no K type thermocouple specific pins that come with the connector. Obviously the pins must be the same metal as the thermocouple or the reading will be incorrect. I am confused as plenty of members here have wired thermocouples without issue. Can anyone offer guidance as to what others have done to wire thermocouples or tell me where to find thermocouple pins? Thanks.

[TimH]

I'm sure Pat will give you the thoroughly detailed technical answer but, in essence, temperatures measured using a thermocouple are based on the voltage difference between the measurement point of interest and a cold reference. The cold reference is (in) the ECU. A transition via an intermediate metal is inevitable and as long as the temperature and intermediate metal of the connection points of both the thermocouple wires is the same, the voltage measured won't change: and I think that since that point is on the same proximity as the cold reference it "helps" as well.

Bottom line...it's fine

[RICE RACING]

No such thing as Thermocouple pins so no problem there.

If you are measuring low temps with this ECU there is a temperature drift that happens after the ECU has been powered from cold start that gives a permanent ~3deg C positive offset, so they will always read this much more than actually exists, its an internal 'thing' that one day will be fixed I've been told.

For EGT measures 3deg C above actual readings though is a non issue

p.s. My old Pectel MQ12 had this exact same temp drift as well fwiw

[TimH]

No such thing as Thermocouple pins so no problem there.

Not strictly true - you can get Alumel and Chromel pins for Deutsch connectors (and others) but they are about £20 each

If you are measuring low temps with this ECU there is a temperature drift that happens after the ECU has been powered from cold start that gives a permanent ~3deg C positive offset, so they will always read this much more than actually exists, its an internal 'thing' that one day will be fixed I've been told.

Interesting! While developing my I/O expander's EGT amplifier, I noticed this error on my S6 and after some investigations and checks I concluded there was, indeed, an error that isn't there in the expander. Same design as S8 I guess?

I imagine that the design means that there is a temperature difference at the two EGT pins after a while, and it needs to recalibrate or something.